1. Field of Invention
The invention is directed to actuator devices for actuating downhole tools and, in particular, actuator devices having a material releases a gas that builds up sufficient pressure to facilitate activation of the actuator device and, thus, actuation of the downhole tool.
2. Description of Art
Some downhole tools need to be retained in an unset position until properly placed in the well. It is only when they are properly located within the well that the downhole tool is set through actuation of the tool. One prior technique for actuating the downhole tool is to open a window or passageway within the downhole tool exposing the actuating member, e.g., piston, of the downhole tool to the wellbore environment, e.g., the hydrostatic wellbore pressure. The hydrostatic pressure then acts upon the actuating member of the downhole tool and the downhole tool is actuated. In this technique, the creation of the window or passageway does not directly actuate the downhole tool. Instead, the creation of the window or passageway allows a different actuating mechanism, e.g., the hydrostatic or wellbore pressure, to actuate the tool. Additionally, in some instances, hydrostatic pressure is insufficient to actuate the tool.
In other prior attempts, pressures from fluids pumped down the well are used to break shear pins on the downhole tools. The use of shear pins, however, requires elevated directional pressure forces acting on the shear pins. However, in some instances sufficient pressure may not be available. Alternatively, in some wells, pressure, even if available, cannot be utilized because additional intervention steps are required which results in the well experiencing undesirable “downtime” for the additional intervention steps. Additionally, in some instances, the shear pins fail to shear when they are supposed to, causing further delays.
In still another prior technique, an explosive charge is included as part of the downhole tool. The explosive charge is then detonated by a detonator connected to the surface of the well through an electronic line or connected to battery pack located on the downhole tool. The force from the combustion of the explosive change then acts upon the actuating member and the downhole tool is actuated. Alternatively, smoke from the explosive charge that was activated by the heat from the battery or the electronic line may also act against the actuating member to actuate the downhole tool.